Display and article with label

ABSTRACT

The present invention provides a display exhibiting high anti-counterfeiting effects and special visual effects. The display of the present invention includes a relief structure-forming layer having a plurality of relief structure-forming areas that are provided on one principal surface side of a light transmissive base, a light reflection layer covering at least a part of the relief structure-forming layer, and a light scattering layer provided on a light reflection layer side of the relief structure-forming layer. The plurality of relief structure-forming areas have a plurality of convexities or a plurality of concavities having a first surface substantially parallel to the principal surface and a second surface substantially parallel to the first surface. In each of the plurality of relief structure-forming areas, a difference in height between the first and second surfaces is substantially constant, and at least one of a difference in height between the first and second surfaces and a height of a virtual plane configured by the first surface is different from the difference in height or a height of the virtual plane of other relief structure-forming areas. The plurality of relief structure-forming areas are arranged in accord with a color image to be displayed.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/832,511, filed on Aug. 21, 2015, which is a Bypass Continuation ofInternational Patent Application No. PCT/JP2014/000938, filed on Feb.21, 2014, which is based upon and claims the benefit of priority ofJapanese Patent Application Nos. 2013-032205, filed on Feb. 21, 2013,and 2013-186245, filed on Sep. 9, 2013. The entire contents of which arehereby incorporated by reference in their entireties.

BACKGROUND

The present invention relates to a display technique that contributes toexerting anti-counterfeiting effects.

Generally, valuable stock certificates, such as gift tickets or checks,cards, such as credit cards, cash cards or ID cards, and certificates,such as passports or driver's licenses, are each adhered with a displayhaving visual effects different from those of a normal printed object,for the purpose of preventing counterfeiting of these articles. Further,recently, circulation of counterfeit articles besides these articles isalso becoming a social problem. Therefore, there are increasingopportunities of applying similar anti-counterfeiting technique to sucharticles as well.

As described in the specification of US-B-5058992, a display exertingvisual effects different from those of a normal printed object uses amethod of arranging a plurality of relief-type diffraction gratingshaving grooves whose longitudinal directions or grating constants (i.e.pitches of grooves) are different from each other, and displaying aniridescently changing image. However, lots of articles needing measuresfor preventing counterfeit have used such a display that includesrelief-type diffraction gratings. As a result, this technique is nowwidely known. Along with this, there is a tendency that counterfeitarticles that have incorporated this technique are increasingly common.Therefore, it is now more difficult to achieve sufficientanti-counterfeiting effects using a display only characterized byiridescent light that is due to diffracted light.

In order to achieve more sufficient anti-counterfeiting effects,JP-B-4983899 discloses a display that realizes special visual effectswhich are different from those of conventional relief-type diffractiongrating. JP-B-4983899 discloses a display provided with a concavo-convexstructure which is configured by arranging a plurality of convexitieshaving an upper surface that is substantially parallel to a base surfaceor a plurality of concavities having a bottom surface that issubstantially parallel to the base surface, and a smooth portion that issubstantially parallel to the base surface. This display has a functionof displaying a mixed color which is configured by light of a pluralityof wavelengths, in a predetermined direction. The image shown by thedisplay hardly exhibits color change in an iridescent manner in accordwith the change of position of an illumination source or the position ofan observer, but realizes visual effects that are different from thoseof the conventional relief-type diffraction grating aimed toanti-counterfeit. As a result, a display exerting high eye-catchingeffects (effects of attracting people's attention) and highanti-counterfeiting effects can be realized.

However, the display disclosed in JP-B-4983899 displays only a mixedcolor that is configured by light of a plurality of wavelengths whichare obtained from the concavo-convex structure configured by convexitiesor concavities substantially parallel to the base surface and a smoothportion substantially parallel to the base surface. Therefore, when thedisplay is observed from the back side as well, a color that is the sameas the one observed from the front side of the display is observed. Theconfiguration shown in JP-B-4983899 is not able to achieve the visualeffects that are different on the front and back and desirable forobtaining higher anti-counterfeiting effects.

SUMMARY OF THE INVENTION

The present invention has been made in light of the circumstances setforth above and has as its object to provide a display that exertsimproved anti-counterfeiting effects and special visual effects, and anarticle with a label.

A first invention is a display including a relief structure-forminglayer having a plurality of relief structure-forming areas that areprovided on one principal surface side of a light transmissive base; alight reflection layer covering at least a part of the reliefstructure-forming layer; and a light scattering layer provided by theside of the light reflection layer of the relief structure-forminglayer, being imparted with light transmission performance, while beingimparted with light scattering performance in at least a part thereof,characterized in that: the plurality of relief structure-forming areashave a plurality of convexities or a plurality of concavities having afirst surface substantially parallel to the principal surface and asecond surface substantially parallel to the first surface; the lightreflection layer is formed in conformity with a shape of the pluralityof convexities or concavities; in each of the plurality of reliefstructure-forming areas, a difference in height between the firstsurface and the second surface is substantially constant; in each of theplurality of relief structure-forming areas, at least one of adifference in height between the first surface and the second surfaceand a height of a virtual plane configured by the first surface isdifferent from the difference in height or a height of the virtual planeof other relief structure-forming areas; and the plurality of reliefstructure-forming areas are arranged in accord with a color image to bedisplayed.

Further, a second invention according to the first invention is thedisplay characterized in that, in each of the plurality of reliefstructure-forming areas, a height of a virtual plane configured by thefirst surface is different from a height of the virtual plane in otherrelief structure-forming areas.

Further, a third invention according to the second invention is thedisplay characterized in that the light scattering layer includes aplurality of light scattering areas having different thicknesses andcorresponding to the relief structure-forming areas.

Further, a fourth invention according to any of the first to thirdinventions is the display characterized in that the display furtherincludes a printed layer in color.

Further, a fifth invention according to any of the first to fourthinventions is the display characterized in that the light scatteringlayer contains spherical microparticles having light scatteringperformance.

Further, a sixth invention according to any of the first to fifthinventions is the display characterized in that the light scatteringlayer is an adhesive layer.

Further, a seventh invention according to any of the first to sixthinventions is the display characterized in that the light scatteringlayer has light scattering performance which is substantially uniform ina unit volume.

Further, an eighth invention according to any of the first to seventhinventions is the display characterized in that the light scatteringlayer has a haze value of not less than 80% and a total lighttransmittance of not less than 30%.

Further, a ninth invention is an article with a display, characterizedin that the article with a label includes a display according to any offirst to eighth inventions, and an article carrying the display.

With the configuration of the present invention, the display includes arelief structure-forming layer having a plurality of reliefstructure-forming areas. The plurality of relief structure-forming areashave a plurality of convexities or a plurality of concavities having afirst surface substantially parallel to a display surface and a secondsurface substantially parallel to the first surface. In each of theplurality of relief structure-forming areas, a difference in heightbetween the first surface and the second surface is substantiallyconstant, and in each of the plurality of relief structure-formingareas, at least either one of a difference in height between the firstsurface and the second surface and a height of a virtual planeconfigured by the first surface is different from the difference inheight or a height of the virtual plane of other reliefstructure-forming areas.

When white illumination is incident on such a structure, a difference iscaused in an optical path length (sum of products of a geometricdistance and a refractive index) between the light reflected by thefirst surface and the light reflected by the second surface.Accordingly, the light corresponding to the difference in the opticalpath length causes interference to mutually weaken light of a specificwavelength. Thus, the emission light emitted from the reliefstructure-forming layer is not white in color but becomes light that isable to display any hue, with a chromatic color created by the specificwavelength which is determined by the difference in height between thefirst and second surfaces.

The light reflection layer formed in conformity with the shape of theconvexities or the concavities of the relief structure-forming layercontributes to more strongly reflecting the incident light to enableclearer display of any hue created by the specific wavelength.

The emission light from the above display hardly changes in aniridescent manner in accord with the change in the position of theillumination and the position of an observer, thereby enabling displayin the same color in a wide observation range.

The display further includes the light scattering layer. When thedisplay is observed from one surface side on which the light scatteringlayer is provided, the emission light is scattered together withspecular reflection components of the incident light, disabling displayof any hue with a chromatic color. When observed from the one surfaceside on which the light scattering layer is provided, the light thatreaches the observer from the display (emission light emitted via thelight scattering layer) changes in accord with the light scatteringperformance of the light scattering layer. Sufficiently high lightscattering performance of the light scattering layer can achievescattered light in a white color that relies on the wavelengthcomponents of white illumination. On the other hand, low lightscattering performance of the light scattering layer can achievescattered light that displays a pastel color whose hue of a chromaticcolor is retained to some extent.

As a result, when the display is observed from a side not provided withthe light scattering layer, one can observe display of any hue (colordisplay) created by the specific wavelength. On the other hand, when thedisplay is observed from the side provided with the light scatteringlayer, one can observe a display of a pastel color created by addingwhite illumination components to the color display, or a display createdby white scattered light (monochromatic display).

Each relief structure-forming area is configured by a plurality ofconvexities or a plurality of concavities having the first surfacesubstantially parallel to a principal surface of the base and the secondsurface substantially parallel to the first surface. In each reliefstructure-forming area, a plane configured by the first surface of theplurality of convexities or concavities is defined to be a virtualplane. In each of the plurality of relief structure-forming areas of thedisplay of the present embodiment, a height of the virtual planerelative to the base surface may be different from the height in otherrelief structure-forming areas. When the light scattering layer isformed on the light reflection layer side in this configuration, thelight scattering layer has a surface on the relief structureforming-layer side, which is in conformity with the plurality ofconvexities or concavities of the relief structure-forming layer, andthe light scattering layer has a surface opposite to the reliefstructure-forming layer, which is substantially smooth. Accordingly, thethickness of the light scattering layer is varied in accord with theheight of the virtual plane relative to the base surface. The lightscattering performance can be controlled by varying the thickness of thelight scattering layer. In other words, an area with a relatively smallthickness allows the light scattering performance to be lower, while anarea with a relatively large thickness allows the light scatteringperformance to be enhanced. When observing the display from one sidethat is provided with the light scattering layer, the difference in thelight scattering performance enables the observer to selectivelyperceive an area where display of any hue created by the reliefstructure-forming layer can be observed, and an area where amonochromatic display created by the scattered light in white color canbe observed.

The present display achieves high anti-counterfeiting effects owing tosuch special visual effects that enable display of different hues on thefront and back.

Further, the relief structure-forming layer is provided with theplurality of relief structure-forming areas having different differencesin height between the first and second surfaces. Thus, light of adifferent color is emitted from each relief structure-forming area.Accordingly, the front side can perform color display with a pluralityof colors, while the back side can also perform multicolor display of adifferent hue (pastel display and monochromatic display). Further,devising the relief structure-forming layer, recognition of a patternmay be disabled on the front side but enabled on the back side.

Further, the display may further include a printed layer in color. Inrespect of a display based on the relief structure-forming layer, thehue is permitted to change via the light scattering layer. Particularly,a display obtained via the light scattering layer is monochromatic in anarea where the light scattering performance is sufficient. However, inrespect of the printed layer, a color display of the same hue isobtained via the light scattering layer. Accordingly, the front side canprovide a display of the same color (color display), while the back sidecan provide a display of a different color.

Further, the light scattering layer may include spherical microparticleshaving light scattering performance. The inclusion of the sphericalmicroparticles in the light scattering layer can achieve high lightscattering performance, can sufficiently scatter the light of thespecific wavelength emitted from the relief structure-forming layer, andcan turn the light into white color emission light. By controlling theparticle size and the filling quantity of the spherical microparticles,the light scattering performance and the light transmission performancecan also be adjusted as desired.

Further, the light scattering layer may be an adhesive layer. The lightscattering layer as an adhesive layer can allow the display to be stuckonto an article which is in need of an anti-counterfeiting function.Furthermore, by permitting the light scattering layer to also serve asan adhesive layer, the necessity of separately providing a lightscattering layer is eliminated to thereby reduce the thickness of thedisplay as a whole.

Further, the light scattering layer may have light scatteringperformance which is substantially uniform in a unit volume. Thesubstantially uniform light scattering performance of the lightscattering layer enables accurate control of the light scatteringperformance in accord with the thickness of the light scattering layer.

Further, each relief structure-forming area can display visuallyrecognizable information as an image, using the change in the lightscattering performance conforming to the thickness of the lightscattering layer that covers the area. In the present display, multistepchange in the height of the virtual plane relative to the base surfacecan achieve a pastel display through the interaction of the lightscattering performance with an optional hue. Also, an image can bedisplayed using light and shade of the pastel display. This image, whenobserved from the light scattering layer side, is achieved by thedifference in height between the virtual plane and the base surface. Onthe other hand, when the present display is observed from the reliefstructure-forming layer side, no difference is caused in the displaycolor due to the difference in the height. Accordingly, this enablesdisplay of different hues on the front and back and/or different imageson the front and back. The anti-counterfeiting effects can be furtherenhanced by the use of a painted pattern, a logotype, or a mark as thelight-and-shade image mentioned above.

Further, the light scattering layer may have a haze value of not lessthan 80% and a total light transmittance of not less than 30%. When thehaze value of the light scattering layer is not less than 80% but notmore than 100%, the light of the specific wavelength emitted from therelief structure-forming layer can be sufficiently scattered to therebyturn the emission light into white scattered light. Further, when thetotal light transmittance of the light scattering layer is not less than30% but not more than 100%, the light emitted from the reliefstructure-forming layer is prevented from being blocked more thannecessary. Thus, an observer is able to perceive light that is a mixtureof the light for displaying a chromatic color created by the reliefstructure-forming layer with the specular reflection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically illustrating a display related to afirst embodiment of the present invention;

FIG. 2 is a plan view schematically illustrating an appearance of thedisplay illustrated in FIG. 1, as observed from a back side;

FIG. 3 is an enlarged cross-sectional view illustrating a layerconfiguration of relief structure-forming areas 11 to 14 illustrated inFIG. 1;

FIG. 4 is a diagram schematically illustrating a state where anarrow-pitch diffraction grating emits +primary diffracted light;

FIG. 5 is a diagram schematically illustrating a state where awide-pitch diffraction grating emits +primary diffracted light;

FIG. 6 is a perspective view illustrating an example of a structure thatcan be applied to the relief structure-forming areas of the displayaccording to the first embodiment;

FIG. 7 is a perspective view illustrating another example of a structurethat can be applied to the relief structure-forming areas of the displayaccording to the first embodiment;

FIG. 8 is a schematic diagram illustrating a state of diffracted lightemitted from a diffraction grating;

FIG. 9 is a schematic diagram illustrating a state of light emitted froma relief structure-forming area;

FIG. 10 is a plan view illustrating the relief structure-forming areaillustrated in FIG. 6;

FIG. 11 is a perspective view illustrating an example of a structurehaving directivity that can be applied to the relief structure-formingareas of the display according to the first embodiment;

FIG. 12 is a schematic diagram illustrating a state of light emittedfrom the relief structure-forming area illustrated in FIG. 11;

FIG. 13 is an enlarged perspective view illustrating an example of astructure of the display according to the first embodiment;

FIG. 14 is a schematic diagram illustrating a behavior of light which isincident on a display and which passes through layers;

FIG. 15 is a cross-sectional view illustrating an example of a favorablelight reflection layer;

FIG. 16 is a cross-sectional view illustrating an example of anunfavorable light reflection layer;

FIG. 17 is a cross-sectional view illustrating an example of anunfavorable light reflection layer;

FIG. 18A is a plan view illustrating a pattern of reliefstructure-forming areas according to a second embodiment of the presentinvention;

FIG. 18B is a cross-sectional view illustrating the reliefstructure-forming areas according to the second embodiment of thepresent invention;

FIG. 19 is a plan view illustrating an appearance of a display accordingto the second embodiment, as observed from a back side;

FIG. 20 is a cross-sectional view illustrating an example of a schematicconfiguration according to a third embodiment of the present invention;

FIG. 21 is a plan view illustrating a difference in display between arelief structure-forming layer and a printed layer, as viewed from arelief structure-forming layer side;

FIG. 22 is a plan view illustrating a difference in display between arelief structure-forming layer and a printed layer, as viewed from alight scattering layer side;

FIG. 23 is a plan view schematically illustrating an example of anarticle with a label related to a fourth embodiment of the presentinvention; and

FIG. 24 is a cross-sectional view taken along the line XXIV-XXIV of thearticle with a label illustrated in FIG. 23.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

With reference to the drawings, hereinafter are specifically describedsome embodiments of the present invention. It should be noted that,throughout the drawings, components identical with or analogous to eachother are given the same reference signs for the sake of omittingsimilar descriptions.

FIG. 1 is a plan view schematically illustrating a display 1 accordingto a first embodiment of the present invention. FIG. 2 is a plan viewillustrating an appearance of the display 1 illustrated in FIG. 1, asobserved from a back side. FIG. 3 is a cross-sectional view of reliefstructure-forming areas 11 to 14 of the display 1 illustrated in FIG. 1.In the Figures, the x direction and y direction are parallel to adisplay surface of the display 1, while being perpendicular to eachother. Further, the z direction is perpendicular to the x and ydirections. In the display 1, a relief structure-forming layer 10 sideis defined to be a “front side” and a light scattering layer 40 side isdefined to be a “back side”.

First Representative Embodiment

(Configuration of Display)

As shown in FIG. 1, the display 1 has a front side on which a pluralityof relief structure-forming areas 11 to 14 are arranged to display theletters “TP”. As will be described later, the relief structure-formingareas 11 and 12 show respective different display colors that are causedby the differences in structure height of a plurality of convexitiesformed inside the respective areas. The relief structure-forming area 13has convexities whose structure height is substantially the same as thatin the relief structure-forming area 11. Similarly, the reliefstructure-forming area 14 has convexities whose structure height issubstantially the same as that in the relief structure-forming area 12.Accordingly, the relief structure-forming areas 11 and 13 show displaycolors of the same hue, while the relief structure-forming areas 12 and14 show display colors of a hue different from that of 11 and 13.

In the relief structure-forming areas 11 and 13, the convexities havesubstantially the same structure height, but respective virtual planes111 and 113, which are configured by a first surface 21, have differentheights relative to a base surface 110. Similarly, in the reliefstructure-forming areas 12 and 14 as well, the convexities havesubstantially the same structure height, but respective virtual planes112 and 114, which are configured by the first surface 21, havedifferent heights relative to the base surface 110. In other words, inthe relief structure-forming area 11, at least either of a difference inheight between the first surface 21 and a second surface 22 and theheight of the virtual plane 111 relative to the base surface 110 isdifferent from that in the relief structure-forming areas 12 to 14. Thesame applies to the relief structure-forming areas 12 to 14.

As shown in FIG. 2, on a back side of the display 1, the direction ofthe letters “TP” is inverted to display a so-called mirror script. Whenthe display 1 is observed from the back side as shown in FIG. 2, theletters are observed with a hue different from that observed from thefront side as shown in FIG. 1, which is based on a principle that willbe described later. In an observation from the front side as shown inFIG. 1, the letters “TP” and the background are represented by twocolors. On the other hand, in an observation from the back as side shownin FIG. 2, an image is displayed with hues that are different betweenlight scattering areas 15 to 18, or displayed with a total of four hues.

As shown in FIG. 3, the relief structure-forming layer 10, which islight transmissive, is provided with a plurality of convexities 20configured by the first surface 21 which is smooth and substantiallyparallel to the base surface 110 of the display 1, and the secondsurface 22 which is substantially parallel to the first surface 21. Thefirst and second surfaces 21 and 22 indicate an upper surface (topsurface) and a lower surface (bottom surface), respectively, of theconvexities 20. The first and second surfaces 21 and 22 are in acomplementary relationship. Accordingly, either of the surfaces mayserve as an upper surface, and the other one of them may serve as alower surface. The same applies when the upper and lower surfacerelationship is inverted.

The relief structure-forming areas 11 to 14 are areas where theplurality of convexities 20 of the relief structure-forming layer 10 areformed. In the present invention, the expression “structure height ofconvexity 20” refers to a difference in height between the first andsecond surfaces 21 and 22. The display 1 has a plurality of reliefstructure-forming areas which are provided with the convexities 20 ofdifferent structure heights. In the configuration shown in FIG. 3, thedifferences in height in the relief structure-forming areas 11 and 13are substantially the same, and the differences in height in the reliefstructure-forming areas 12 and 14 are substantially the same.

The difference in height in a set of the relief structure-forming areas11 and 13 is different from the difference in height in a set of therelief structure-forming areas 12 and 14. When observed from the frontside as shown in FIG. 1, the present display 1 realizes a multicolordisplay due to the presence of the plurality of relief structure-formingareas having different differences in height between the first andsecond surfaces 21 and 22.

In each of the relief structure-forming areas 11 to 14, a plane thatincludes the first surface 21 of the plurality of convexities is definedto be a “virtual plane”. In the configuration shown in FIG. 3, virtualplanes 111 to 114 of the relief structure-forming areas 11 to 14,respectively, have mutually different heights relative to the basesurface 110.

The relief structure-forming areas 11 to 14 are obtained by replicatinga relief structure from an original plate which is manufactured by meansof lithography. For example, a plate-shaped substrate, with its one mainsurface being coated with a photosensitive resist, is placed on an XYstage, followed by radiating electron beams in a pattern to thephotosensitive resist under computer control while the stage is moved,thereby forming an original plate. Then, a metal stamper is fabricatedfrom the original plate by means of electrocasting or the like. Then,using the metal stamper as a matrix, a relief structure is replicated.Specifically, a thermoplastic resin, a thermosetting resin or aphoto-curable resin is coated, first, onto a film or sheet of thintransparent base made of polyethlene terephthalate (PET) orpolycarbonate (PC). Then, the coated resin layer is brought intointimate contact with the metal stamper, and in this state, heat orlight is applied to the resin layer. After completion of plasticdeformation or curing of the resin, the metal stamper is separated fromthe resin layer, thereby obtaining a relief structure.

Further, a light reflection layer 30 is formed in conformity with theplurality of convexities provided to the relief structure-forming layer10. The light reflection layer 30 covers at least a part of the reliefstructure-forming layer 10. Further, the light scattering layer 40 isformed on a light reflection layer 30 side of the reliefstructure-forming layer 10. The light scattering layer 40 covers thelight reflection layer 30. If there is an area that is not covered withthe light reflection layer 30 in the relief structure-forming layer 10,the light scattering layer covers the non-covered area of the reliefstructure-forming layer 10. A surface which is opposite to the lightreflection layer 30 side of the light scattering layer 40 is a planethat is substantially parallel to the base surface 110. The lightscattering layer 40 has light scattering performance which is achieved,not by the relief pattern whose structure is exposed to the surface, butby light scattering elements contained inside the layer as will bedescribed later. In the configuration shown in FIG. 3, the reliefstructure-forming layer 10 is entirely covered with the light reflectionlayer 30, while the light reflection layer 30 is covered with the lightscattering layer 40.

The light scattering layer 20 has a plurality of light scattering areasat positions corresponding to the respective plurality of reliefstructure-forming areas. In the configuration shown in FIG. 3, the lightscattering areas 15 to 18 are provided so as to correspond to the reliefstructure-forming areas 11 to 14, respectively, and be located at thesame respective positions in the z-axis direction. The light scatteringareas 15 to 18 have mutually different heights in accord with therespective heights of the virtual planes 111 to 114 relative to the basesurface 110.

Materials that can be used as the relief structure-forming layer 10include, for example, synthetic resins, such as photo-curable resins,thermoplastic resins, or thermosetting resins.

A metal layer can be used as the light reflection layer 30, the metallayer being made of a metallic material, such as aluminum, silver, gold,or an alloy of these materials. Alternatively, a dielectric layer may beused as the light reflection layer 30, the dielectric layer being madeof a material such as zinc sulfide (ZnS), titanium oxide (TiO2), or thelike. Alternatively, a dielectric multilayer film may be used as thelight reflection layer 30. The dielectric multilayer film in this caseis a lamination of dielectric layers having different refractive indexesbetween adjacent layers. For example, the light reflection layer 30 canbe formed by means of a vapor phase deposition method, such as vacuumvapor deposition or sputtering.

The light reflection layer 30 efficiently reflects and emits lightincident on the display 1 to contribute to increasing the quantity ofreflected light. The light reflection layer 30 may be formed so as toentirely cover the plurality of convexities 20 of the reliefstructure-forming layer 10, or may be formed so as to cover only some ofthe convexities. The light reflection layer 30 covering only a part ofthe relief structure-forming layer 10 may be graphically patterned intodesign letters, symbols, or the like. A patterned light reflection layer30 is obtained, for example, by forming the light reflection layer 30 asa continuous film by a vapor phase deposition method, followed bypartially dissolving the film such as by chemicals. Alternatively, afterforming the light reflection layer 30 as a continuous film, the film maybe partially separated from the relief structure-forming layer 10 usingan adhesive material having a higher adhesive force relative to thelight reflection layer 30, compared to the sticking force of the lightreflection layer 30 relative to the relief structure-forming layer 10,thereby obtaining a patterned light reflection layer 30. Alternatively,a method of performing vapor phase deposition using a mask or a methodof using a lift-off process may be used.

The light scattering layer 40 has light transmission performance andalso at least partially has light scattering performance. The lightscattering layer 40 may be formed of a light transmissive syntheticresin in which spherical microparticles that are capable of scatteringlight are scattered. The spherical microparticles may be resin particlesor inorganic particles mainly composed of a metallic compound. Theresins that can be used include silicone resins, acrylic resins, styreneresins, acrylic styrene resins, melamine resins, and the like. Themetallic compounds that can be used include zinc oxide, alumina,titanium oxide, and the like. Alternatively, a semi-transparent inklayer having light scattering performance may be used.

It should be noted that the display 1 may further include a layer, suchas a printed layer and/or a surface protective layer, which is able toachieve other functions.

(Regarding Optical Performance of Diffraction Grating)

Prior to describing the visual effects achieved by the concavo-convexstructure formed in the relief structure-forming areas of the display 1,there is described first a relationship between the grating constant ofa diffraction grating (pitch of grooves), the wavelength ofillumination, the incident angle of illumination, and the emission angleof diffracted light.

When illumination is applied to a diffraction grating by means of anillumination source, the diffraction grating emits strong diffractedlight in a specific direction, according to the traveling direction andthe wavelength of the illumination that is incident light.

An m-order diffracted light beam (m=0, ±1, ±2, . . . ) has an emissionangle β which can be calculated from the following Formula (1) when thelight travels in a plane perpendicular to a longitudinal direction ofthe grooves of the diffraction grating.

$\begin{matrix}{\left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack \;} & \; \\{d = \frac{m\; \lambda}{{\sin \; \alpha} - {\sin \; \beta}}} & (1)\end{matrix}$

In Formula (1), d represents a grating constant of a diffractiongrating, m represents a diffraction order, and λ represents a wavelengthof incident light and diffracted light. Further, a represents anemission angle of a 0-order diffracted light beam, i.e. specularreflection RL. In other words, α has an absolute value which is equal tothe incident angle of illumination. In the case of a reflection grating,the incident direction of illumination and the emission direction ofspecular reflection are symmetric about a normal line NL of an interfacewhere the diffraction grating is provided.

When the diffraction grating is of a reflection type, the angle α is 0°or more, but less than 90°. Let us discuss the case where illuminationis applied from a direction oblique to the interface where thediffraction grating is provided. In this case, taking two angular rangeswith an angle in a normal direction, i.e. 0°, as being a boundary value,the angle β will have a positive value if the emission directions of thediffracted light and the specular reflection fall in the same angularrange, but will have a negative value if the emission direction of thediffracted light and the incident direction of the illumination fall inthe same angular range.

FIG. 4 is a diagram schematically illustrating the specular reflectionRL and primary diffracted light beams emitted by a diffraction gratinghaving a small grating constant d. FIG. 5 is a diagram schematicallyillustrating a state where a diffraction grating having a large gratingconstant d emits the specular reflection RL and primary diffracted lightbeams.

A point source LS radiates white illumination IL that contains a lightcomponent R whose wavelength is in a red color area, a light component Gwhose wavelength is in a green color area, and a light component B whosewavelength is in a blue color area. The light components G, B and Rradiated by the point source LS are incident on a diffraction grating GRat the incident angle α. The diffraction grating GR emits a diffractedlight beam GL_g as a part of the light component G at an emission angleβ_g (not shown), emits a diffracted light beam GL_b as a part of thelight component B at an emission angle β_b (not shown), and emits adiffracted light beam GL_r as a part of the light component R at anemission angle β_r. Although not shown, the diffraction grating GR alsoemits diffracted light beams of other orders at angles each derived fromFormula (1).

In this way, under predetermined illumination conditions, a diffractiongrating emits diffracted light beams at different angles, depending onthe wavelength. Therefore, under a white light source, such as the sunor a fluorescent light, a diffraction grating emits light of differentwavelengths at different angles. Accordingly, under such illuminationconditions, a diffraction grating shows a display color which changes inan iridescent manner according to the change of an observation angle.Further, as the grating constant d is larger, diffracted light isemitted in a direction that is more approximate to the specularreflection RL, making the difference between the emission angles, β_g,β_b and β_r smaller.

The following is a description on a relationship between: the gratingconstant of a diffraction grating, the wavelength of illumination, andthe intensity of diffracted light in an emission direction of thediffracted light (diffraction efficiency).

According to Formula (1), when illumination is incident on a diffractiongrating having the grating constant d at the incident angle α, thediffraction grating emits a diffracted light beam at the emission angleβ. In this case, the diffraction efficiency in respect of the lighthaving the wavelength λ changes, depending such as on a grating constantof the diffraction grating and the depth of grooves, and can becalculated from the following Formula (2).

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 2} \right\rbrack & \; \\{\eta = {\left( \frac{2}{\pi} \right)^{2} \times {\sin^{2}\left( {\frac{2\; \pi}{\lambda} \times \frac{r}{\cos \; \theta}} \right)} \times {\sin^{2}\left( {\frac{\pi}{d} \times L} \right)}}} & (2)\end{matrix}$

In the formula, η represents a diffraction efficiency (value from 0 to1), r represents a depth of grooves of the diffraction grating, Lrepresents a width of each groove of the diffraction grating, drepresents a grating constant, θ represents an incident angle ofillumination, and λ represents a wavelength of illumination anddiffracted light. It should be noted that Formula (2) is established fora diffraction grating having a rectangular wave-like cross sectionperpendicular to a longitudinal direction of grooves, the grooves beingcomparatively shallow.

As is obvious from Formula (2), the diffraction efficiency η changesaccording to the depth r of the grooves, the grating constant d, theincident angle θ, and the wavelength λ. Further, the diffractionefficiency η tends to be gradually lowered as the diffraction order mbecomes higher.

(Regarding optical performance achieved by relief structure-forminglayer)

The following description deals with optical performance achieved by therelief structure-forming areas which are formed in the reliefstructure-forming layer 10.

FIG. 6 is a perspective view schematically illustrating an example of aconcavo-convex structure that can be used for a relief structure-formingarea. The relief structure-forming area 11 includes the second surface22, which is smooth, and the plurality of convexities 20 each having anupper surface and a side surface. The upper surface of each convexity 20is parallel to the second surface 22 and serves as the first surface 21which is smooth.

It should be noted that FIG. 6 shows an example in which the reliefstructure-forming area 11 is formed of the plurality of convexities 20,with the first surface 21 configuring the upper surface (top surface) ofeach convexity 20 and the second surface 22 configuring a lower surface(bottom surface) of each convexity 20. However, in the case where aplurality of concavities are formed in the relief structure-forming areaand the second surface is configured by a plurality of bottom surfacesof the concavities as well, the optical performance set forth below issimilar. Hereinafter, the optical performance is described with theillustration of a plurality of convexities, omitting illustration anddescription of a plurality of concavities.

In FIG. 6, the convexities 20, each being in a circular shape, arearranged in an orderly manner relative to a predetermined direction onone surface of the relief structure-forming area 11. The arrangement inan orderly manner refers to the convexities 20 being arrayed with aneven interval therebetween or with regularity. The orderly arrangedplurality of convexities 20 form, for example, a square grating, arectangular grating or a triangular grating.

FIG. 7 is a perspective view illustrating an example of anotherstructure that can be applied to a relief structure-forming area. Theconvexities 20 in a circular shape are arranged in a disordered manner(arranged at random) in the relief structure-forming area 11. In thecase where the convexities 20 are arranged in a disordered manner, theconvexities 20 may be formed in a mutually overlapped state.

Each convexity 20 may be in any polygonal shape, such as an ellipticshape, an octagonal shape, a star shape or a cross shape. Alternatively,convexities of different shapes may be combined together in a reliefstructure-forming area.

FIG. 8 is a schematic diagram illustrating a state of diffracted lightwhich is emitted when the illumination IL of white color is radiatedonto a normal diffraction grating. FIG. 8 shows a diffraction grating GRcomposed of a plurality of grid lines which are regularly formed in adirection parallel to the y axis. When the illumination IL is incidenton the diffraction grating GR, the diffracted light beams DL_r, DL_g andDL_b are emitted in a direction perpendicular to the y axis(longitudinal direction of the grid lines) (in an x-axis direction, i.e.in an xz plane).

On the other hand, FIG. 9 is a schematic diagram illustrating a state ofdiffracted light which is emitted from the relief structure-forming area11 having the plurality of convexities 20. FIG. 10 is a plan viewillustrating the relief structure-forming area 11 illustrated in FIGS. 6and 9.

When white illumination is incident on a structure as shown in FIG. 9,diffracted light is emitted by the plurality of convexities 20 which areformed in the relief structure-forming area 11, or by a concavo-convexstructure configured by the first surface 21 and the second surface 22surrounding the first surface 21. As shown in FIG. 9, in a structurewhere the convexities 20 are orderly arranged being separated from eachother, diffracted light beams are emitted not only in the x-axisdirection (in an xz plane) but also in directions of multiple azimuthalangles on an xy plane (i.e. in a three-dimensional manner).

As indicated in FIG. 10 by the dashed lines A, B and C, although theplurality of convexities 20 are configured to be orderly arranged, thearrangement interval (grating constant d) appears different depending onthe azimuth. Therefore, the relief structure-forming area 11 shown inFIGS. 9 and 10 can be a concavo-convex structure having variousarrangement intervals (grating constants d). When light is incident onsuch a structure, concavo-convex structures of different gratingconstants d can be multiply superimposed. Accordingly, it is not that adiffracted light beam is emitted at an emission angle that is differenton a wavelength-basis, but that the light beams of various wavelengthsare emitted at various angles, being superimposed with each other.

Further, FIG. 9 shows a state where the illumination IL is incident onone point of the relief structure-forming area 11. However, as a matterof fact, the illumination source has an area having some spatial extentand thus the illumination IL is incident in a planar manner, instead ofbeing incident on one point. Accordingly, the light observed by anobserver at a fixed point is a combination of light beams havingwavelengths of some range. As a result, a color created by the lightbeams of a plurality of wavelengths is observed.

As shown in Formula (2), the diffraction efficiency, i.e. lightquantity, of diffracted light emitted from a diffractive structurechanges depending on the wavelength. Particularly, when a grid linewidth L and a pitch d of the grid lines are taken as being fixed, thediffraction efficiency η is univocally determined according to theheight r (corresponding to the difference in height between the firstand second surfaces 21 and 22) of the diffraction grating and thewavelength λ of the illumination.

Therefore, when the relief structure-forming area 11 is observed from afixed point, the wavelength components of visible light do not uniformlyreach the eye. This is because the diffraction efficiency of the lightof a specific waveform is lowered due to the interference of the lightwhich is in accord with the height (difference in height between thefirst and second surfaces 21 and 22) of the convexities 20 provided inthe relief structure-forming area. As a result, the light that reachesthe observer is decreased in light quantity in respect of the specificwavelength components of the incident white-colored illumination.Accordingly, when the relief structure-forming area 11 is observed underthe white illumination source, the observer will perceive the light inwhich there is a difference in the light quantity on a wavelength-basis.

For example, let us take a situation where a relief structure-formingarea provided with convexities of some height is observed, and in theobservation, the diffraction efficiency of the light of blue (wavelengthof 460 nm) is lowered and thus the wavelength components that reach theobserver's eye are red (wavelength of 630 nm) and green (wavelength of540 nm). In this situation, the observed color is yellow. Let us assumea situation where another relief structure-forming area provided withconvexities of another height is observed, and in the observation, thediffraction efficiency of the light having red wavelength components islowered and thus the wavelength components of the diffracted light thatreach the observer's eye are of green and blue. In this situation, theobserved color is cyan. As an example, FIG. 9 shows a state where theillumination IL from the white illumination source is incident on therelief structure-forming area 11, with the diffracted light beam DL_r(not shown) not being emitted due to the lowering of the diffractionefficiency, but with the green and blue diffracted light beams DL_g andDL_b being emitted.

The display color displayed according to the above principle will not beobserved by an observer if he/she is at a position where the diffractedlight does not reach. Thus, the diffraction grating is able to realizetwo states, one being a state where the display color can be recognized,and the other being a state where the display color cannot berecognized, depending on the position of the illumination source or theobserver. This is what is different from a normal printed object fromwhich substantially the same color can be perceived in a great deal ofrange.

Diffracted light is emitted as well in the relief structure-forming area11 shown in FIG. 7 where the plurality of convexities 20 are arranged ina disordered manner. In the relief structure-forming area 11 shown inFIG. 7, the grating constant d shown in Formula (1) has various values.Accordingly, the emission angle of the diffracted light variouslychanges according to the illuminating position of the illumination IL.Therefore, similar to the structure shown in FIG. 6 where the pluralityof convexities 20 are arranged in an orderly manner, the diffractedlight that reaches an observation point is the light of multiplewavelengths with an exception of the light of a specific wavelength. Atthe observation point, a mixed color of these light beams is observed.Compared to the structure of an orderly arrangement as shown in FIG. 6,use of the relief structure-forming area 11 having the plurality ofconvexities 20 arranged in a disorderly manner will result in emittingthe light of various wavelengths across a wider angle range. This effectcan contribute to realizing a display in which the iridescent colorchange caused by diffraction is more suppressed.

Thus, on the condition that the light from an illumination source isincident on the surface of the display 1 and the incident light isreflected and emitted by the relief structure of the display 1, anobserver can visually perceive the light. This condition is defined tobe a “normal illumination condition”. For example, the “normalillumination condition” includes a condition where illumination such asof a fluorescent light of an interior of a normal room is substantiallyvertically incident on the surface of the display 1 and an observervisually observes the display 1, or a condition where illumination suchas of the sun is substantially vertically incident on the surface of thedisplay 1 outside a room, and an observer visually observes the display1. Herein, an expression “normal illumination” refers to the light froma fluorescent light in the interior of a room, and the illumination of awhite color such as of the sun outdoors. Further, an expression“condition other than the normal illumination condition” refers to acondition where an observer cannot perceive the light emitted from thedisplay 1. For example, the “condition other than the normalillumination condition” includes a condition where the light ofillumination is substantially horizontally incident (i.e. at a largeincident angle) on the surface of the display 1 but the light is hardlyemitted from a relief structure of the display 1, or a condition wherelight is emitted by diffraction from a relief structure of the display 1but an observer sees the display 1 from an angle at which the diffractedlight does not reach the observer.

In order to provide a structure that enables observation of a colorcomposed of the light of a plurality of wavelengths under the normalillumination condition, it is desirable that each of the convexities 20orderly arranged as shown in FIG. 6 (if each convexity 20 has a circularfirst surface 21, the diameter of the circle) has a slightly largerstructure with a dimension of about 5 μm to about 10 μm. Adjacentconvexities 20 may have an arrangement interval, for example, rangingfrom about 5 μm to 10 μm. As is apparent from Formula (1) and FIG. 5,the differences between the emission angles of the diffracted light foreach wavelength are small in the case of a large structure with adimension and an arrangement interval falling in the above range.Accordingly, irrespective of the change in the position of anillumination source and/or of an observer, the display color does notcause a so-called iridescent change, thereby enabling stable observationof the color created by the light of a plurality of wavelengths.

On the other hand, it is desirable that each of the convexities 20 inthe disordered arrangement as shown in FIG. 7 has a slightly smallerstructure with a dimension of about 0.3 μm to about 5 μm. Further,adjacent convexities 20 may have an arrangement interval ranging, forexample, from 0.3 μm to 5 μm. As is apparent from Formula (1), thedifferences between the emission angles of the diffracted light for eachwavelength are large in the case of the small structures that are formedwith a small arrangement interval therebetween. Therefore, in thestructure of a disordered arrangement, an iridescent color change tendsto be easily caused, while the light of multiple wavelengths ispermitted to easily reach an observation point. Further, as is apparentfrom Formula (1) and FIG. 4, the disordered arrangement of the smallstructures increases the differences between the emission angles of thediffracted light and accordingly provides an advantage of enablingobservation of a display color of multiple light beams in a wide range.

The relief structure-forming areas each use the structure in which thedifferences in height between the first and second surfaces 21 and 22forming the concavo-convex structure are substantially the same. Such astructure has an effect of lowering the diffraction efficiency of thelight of a specific wavelength by light interference, and suppressinglowering of the diffraction efficiency of the light of otherwavelengths. Therefore, the structure in which the differences in heightbetween the first and second surfaces 21 and 22 are substantially thesame enables display of a unique chromatic color created by the light ofmultiple wavelengths which do not lower the diffraction efficiency. Ifthe differences in height between the first and surfaces 21 and 22forming the concavo-convex structure are not substantially the same, thewavelength range of light, in which the diffraction efficiency islowered, is enlarged. As a result, the chroma of the obtained displaycolor is lowered and approximated to a white color with a wavelengthdistribution which is hardly different from that of the incident light.In a generally used light scattering structure, fine structures areirregularly arranged and the depths of the structures are alsoirregular. Accordingly, the performance of lowering the diffractionefficiency of the light of a specific wavelength is not available,resultantly allowing the incident white light to be scattered andemitted as it is to thereby present a white display color. Therefore,for enabling display of a chromatic and specific unique color, thedifferences in height between the first and second surfaces 21 and 22are required to be substantially the same.

The differences in height between the first and second surfaces 21 and22 for exerting such optical effects are within a range, for example, offrom 0.1 μm to 0.5 μm, typically from 0.15 μm to 0.4 μm. Smallerdifferences in height between the first and surfaces 21 and 22 lowersthe chroma of the light of the chromatic color, which is emitted fromthe relief structure-forming area. Further, smaller differences inheight increase the effect on the optical characteristics of the reliefstructure-forming area, the effect being caused by slight change in anexternal factor at the time of manufacture (e.g., change in theconditions and environment of a manufacturing apparatus, and/or materialcompositions). On the other hand, large differences in height make itdifficult to form the relief structure-forming area with high accuracyin shape and dimension.

Each convexity has a side surface which typically is perpendicular tothe first and second surfaces. The side surface may be inclined relativeto the first and second surfaces. In this case, however, the sidesurface of each convexity is desirably more vertical. As the sidesurface more inclines, the chroma of the display color is more lowered.

As shown in FIG. 9, the structure used for the relief structure-formingarea emits diffracted light in the directions of multiple azimuthalangles on the xy plane. Accordingly, a color configured by a pluralityof wavelengths can be observed, irrespective of a slight change in theposition of the light source or the direction of the observation. Thiscan help avoid or decrease the occurrence of the phenomenon of aniridescent change in a display color, which phenomenon would otherwisehave occurred in a conventional diffraction grating under the normalillumination condition.

Still another structure that can be used for a relief structure-formingarea includes a structure having directivity. FIG. 11 is an example ofthe relief structure-forming area 11 composed of a plurality of linearlystructured convexities 20, each being in a shape extended in the y-axisdirection. Each convexity 20 has a width, for example, ranging from 0.2μm to 10 μm, typically ranging from 0.3 μm to 5 μm. Each convexity 20has a length ratio relative to the width, for example, of two or more,or typically, ten or more. A smaller ratio than this will make itdifficult for an observer to perceive optical anisotropy describedlater.

The plurality of convexities 20 are arrayed so as not to configure adiffraction grating or a hologram which emits diffracted light that canbe perceived with the naked eye. Herein, distances between the centerlines of adjacent convexities 20 in a width direction are irregular.Either the distances between the centers of the convexities 20 or thewidths of the convexities may be equal to each other.

The convexities that are adjacent in a width direction have anarrangement interval therebetween, ranging, for example, from 0.2 μm to10 μm, typically from 0.3 μm to 5 μm. The convexities 20 have variouslengths. The positions of the convexities 20 in a longitudinal directionare irregular. The convexities 20 may have an equal length, or may beregularly arranged in a longitudinal direction.

As shown in FIG. 12, when the illumination IL in white color is incidenton such a structure from vertically above the display 1, the incidentillumination IL emits the diffracted light beams DL_g and DL_b in the xzplane, along a direction perpendicular to the longitudinal direction ofthe convexities 20 (x-axis direction), but does not emit diffractedlight beams in the longitudinal direction of the convexities 20 (y-axisdirection). In FIG. 12, the height of the convexities 20 (i.e. thedifference in height between the first and second surfaces 21 and 22) ispermitted to be the same as the height of the structure shown in FIG. 10to show a state where the diffraction efficiency of the red diffractedlight beam DL_r (not shown) is lowered and a cyan display color isobtained.

In this way, provision of a structure having directional properties(directivity) enables control of an azimuthal direction in which thediffracted light is emitted. In this case as well, by equalizingdifferences in height between the first and second surfaces 21 and 22,the diffraction efficiency of light with a specific wavelength islowered in accord with the differences in height. Accordingly, thediffracted light observed in a direction perpendicular to a longitudinallength of the convexities 20 (x-axis direction) displays a uniquechromatic color. Further, since the plurality of convexities 20 arearranged at random, the display color does not change in an iridescentmanner. Accordingly, the same unique chromatic color is displayed in awide range in a direction perpendicular to a longitudinal length of theconvexities 20 (x-axis direction).

When S is taken as an area of an orthogonal projection of the reliefstructure-forming area 11 onto a plane parallel to the first and secondsurfaces 21 and 22, the ratio of an area S1 of the first surface 21 tothe area S as expressed by S1/S ranges, for example, from 20% to 80%,typically 40% to 60%. Further, the ratio of an area S2 of the secondsurface 22 to the area S as expressed by S2/S ranges, for example, from80% to 20%, typically from 60% to 40%. Further, the ratio of the sum ofthe areas S1 and S2, i.e. S1+S2, to the area S as expressed by (S1+S2)/Sranges, for example, from 10% to 100%, typically from 50% to 100%. Adisplay of highest luminance can be achieved when the ratios S1/S andS2/S are each 50%. According to an example, when one of the ratios S1/Sand S2/S is 20% and the other is 80%, the luminance that can be achievedis about 30% of the luminance that can be achieved when the ratios S1/Sand S2/S are each 50%.

The light which is incident on the concavo-convex structure or thediffraction grating formed on the relief structure-forming layer 10 ofthe display 1 is emitted as emission light in a predetermined directionaccording to the principle of diffraction. Besides, the specularreflection (regular reflection) RL is also emitted in a speculardirection relative to an incident angle direction of the incident light.This light corresponds to a component of light that is emitted withoutbeing influenced by the shape of the concavo-convex structure.Generally, when an observer sees the display 1 provided with the lightreflection layer 30, the observer observes the display 1 so that thespecular reflection RL does not penetrate into the eye because thespecular light RL has a large light quantity and causes glare.Illustration of the specular reflection RL is omitted from FIG. 12.

(Regarding Visual Effects Realized By the Display)

FIG. 13 is a schematically enlarged perspective view of an example ofthe configuration of the relief structure-forming layer 10 that can beused in the present embodiment. In FIG. 3, the plurality of convexitieshave been illustrated as being configured downward along the z axis(downward in the drawing sheet). In FIG. 13, the convexities areillustrated as being configured upward along the z axis (upward in thedrawing sheet).

Each of the relief structure-forming areas 11 to 14 is formed with theplurality of convexities 20. In other words, the concavo-convexstructure is configured by the first and second surfaces 21 and 22. Theplurality of convexities 20 in the relief structure-forming areas 11 and13 have substantially the same height. Also, the plurality ofconvexities 20 in the relief structure-forming areas 12 and 14 havesubstantially the same height.

The relief structure-forming areas 11 to 14 have different heights fromthe base surface 110. In other words, as shown in FIG. 3, the heights ofthe virtual planes 111 to 114 (planes each configured by the first plane21) relative to the base surface 110 are different from each other. InFIG. 13, the heights of the virtual planes 111 to 114 (planes eachconfigured by the first surface 21) relative to the base surface 110 areconfigured to be increased in the order of the relief structure-formingareas 11, 12, 13 and 14.

The relief structure-forming layer 10 is configured by a transparent orsemi-transparent, desirably, colorless and transparent material.Therefore, the display 1 can be observed not only from the side wherethe concavo-convex structure is provided, but also from the base surface110 side. The relief structure-forming layer has a smooth firstprincipal surface (base surface 110) and a second principal surfacewhich is opposite to the first principal surface, with theconcavo-convex structure being at least partially formed in the secondprincipal surface.

In the present display 1, the light reflection layer 30 is furtherlaminated on the relief structure-forming layer 10. The light reflectionlayer 30 is a thin film layer configured in conformity with the reliefstructure-forming layer 10 to contribute to efficiently emitting whiteillumination that has been incident on the relief structure-forminglayer 10. In FIG. 13, illustration of the light reflection layer 30 isomitted.

In FIG. 13, when an observer observes the relief structure-forming layer10 from above in the z-axis direction, the observer will perceive thelight reflected and emitted by the concavo-convex structure provided tothe relief structure-forming areas 11 to 14 and by the light reflectionlayer 30 formed in conformity with the concavo-convex structure. Theemission light that reaches the observer indicates a chromatic colorwith any hue created by a specific wavelength determined by thedifferences in height between the first and second surfaces 21 and 22.

The convexities 20 have a structure depth which is different between aset of the relief structure-forming areas 11 and 13 and a set of therelief structure-forming areas 12 and 14. Accordingly, different colorscan be displayed between these sets of areas. The reliefstructure-forming areas 11 to 14 in optional shapes enable expression ofan image, such as a design or a letter, or a numeral or a symbol. FIG.13 illustrates each of the relief structure-forming areas 11 to 14 as asingle area. However, each of the relief structure-forming areas 11 to14 may be configured by a plurality of separate sub-areas. FIGS. 1 and 2show a configuration in which the relief structure-forming areas 11 to13 each are a single area, while the relief structure-forming area 14 iscomposed of two sub-areas (the inside and the outside of the letter“P”).

In the configuration shown in FIG. 13, the relief structure-formingareas 11 to 14 have virtual planes 111 to 114, respectively, havingrespective different heights from the base surface 110. The displayeffects of the chromatic color achieved by the concavo-convex structureprovided in the relief structure-forming areas are not influenced by thedifferences in height of the virtual planes 111 to 114. The displayedhue is univocally determined by the height of the concavo-convexstructure, i.e. the differences in height between the first and secondsurfaces 21 and 22. Specifically, the relief structure-forming areas 11and 13 shown in FIG. 13, although their respective virtual planes 111and 113 are different in height, display the same color because theheight of the concavo-convex structure is substantially uniform. Thesame applies to the relief structure-forming areas 12 and 14.

These visual effects are similar as well when the reliefstructure-forming areas 11 to 14 are observed from the base surface 110side. When the relief structure-forming layer 10 is observed from belowin the z-axis direction as well, the relief structure-forming areas 11and 13 are perceived to be the same color, while the reliefstructure-forming areas 12 and 14 are also perceived to be the samecolor. The hue of the displayed chromatic color only relies on theheight of the concavo-convex structure.

In addition to the relief structure-forming layer 10 and the lightreflection layer 30, the display 1 is further laminated with a lightscattering layer to provide the layer configuration shown in FIG. 3.When an observer observes the display 1 from the back side, the whiteillumination incident on the display 1 is transmitted through the lightscattering layer, reflected by the light reflection layer 30 provided inconformity with the shape of the concavo-convex structure of the reliefstructure-forming layer 10, again transmitted through the lightscattering layer, and reaches the observer's eye.

The light reflected by the light reflection layer 30 provided inconformity with the concavo-convex structure of the reliefstructure-forming layer 10 is the light of a chromatic color with anoptional hue created by the specific wavelength that is determined bythe differences in height of the concavo-convex structure. However, as aresult of the transmission through the light scattering layer, the lightof the specific wavelength and the specular reflection from the lightreflection layer 30 (the light in white color conforming to thewavelength distribution of the white illumination) are mixed, and thusthe light that reaches the observer's eye has a hue which is differentfrom the light observed from the front side.

FIG. 14 is a cross-sectional view illustrating a state where light 61from a white illumination source 60 is incident on the light scatteringlayer 40 of the display 1, and the light emitted after being reflectedby the light reflection layer 30 and again passing through the lightscattering layer 40 reaches an observer 65. In order to illustrate thepath of light, the light scattering layer 40, the reliefstructure-forming layer 10 and the light reflection layer 30 areseparately shown but, as a matter of fact, these layers are configuredto be in intimate contact with each other.

The white illumination 61 emitted from the light source 60 istransmitted through the light scattering layer 40, turning to whitescattered light 64, and reaches the light reflection layer 30. Then, thelight reflection layer 30 which is formed in conformity with theconcavo-convex structure of the relief structure-forming layer 30 emitslight 62 that displays a chromatic color with the specific wavelength,while concurrently emitting specular reflection 63. In this case, thelight 62 of the specific wavelength and the specular reflection 63 areemitted in mutually different directions. The light 62 and the specularreflection 63, when again being transmitted through the light scatteringlayer 40, are scattered and mixed with each other for the emission ofthe scattered light 64 in white color from the scattering layer 40.

When the light scattering layer 40 has sufficient light scatteringperformance, the scattered light 64 is emitted as white light of auniform light quantity across a wide observation range. On the otherhand, when the light scattering performance of the light scatteringlayer 40 is low, the scattered light 64 becomes light of a display colorwith the chroma derived from the original light 62 of the specificwavelength. In other words, the control over the light scatteringperformance of the light scattering layer 40 enables control over thechroma of the display color when the display 1 is observed from thelight scattering layer side.

As shown in FIG. 3, in the display 1, the thickness of the lightscattering layer 40 changes in accord with the height of the virtualplane of the concavo-convex structure from the base surface 110. Whenthe virtual plane is near the base surface 110 (when the height from thebase surface 110 is small), the thickness of the light scattering layer40 becomes relatively large. Contrarily, when the virtual plane is farfrom the base surface 110 (when the height from the base surface 110 islarge), the thickness of the light scattering layer 40 becomes small.When the light scattering performance per unit volume of the lightscattering layer is taken as being uniform, the light scatteringperformance is in proportion to the thickness of the light scatteringlayer 40.

In FIG. 3, the light scattering area 15 corresponding to the reliefstructure-forming area 11 has a small thickness and low light scatteringperformance. Also, the light scattering area 18 corresponding to therelief structure-forming area 14 has a large thickness and high lightscattering performance.

Further, the convexities 20 formed in the relief structure-forming areas11 and 13 have a height that is different from the height in the reliefstructure-forming areas 12 and 14. Therefore, when the display 1 isobserved from the front side (relief structure-forming layer 10 side),the observer can perceive a display created by a total of two chromaticcolors, one being the display color of the relief structure-formingareas 11 and 13, and the other being the display color of the reliefstructure-forming areas 12 and 14.

On the other hand, when the display 1 is observed from the back side(light scattering layer 40 side), the display color of the reliefstructure-forming areas 11 and 13 is influenced by the light scatteringperformance of the respective light scattering areas 15 and 17.Similarly, the display color of the relief structure-forming areas 12and 14 receives the light scattering performance of the respective lightscattering areas 16 and 18. The light scattering areas 15 to 18, whosethickness changes stepwise, have different light scatteringperformances. Accordingly, when observed from the back side (lightscattering layer 40 side), four colors (4-step gradation), instead oftwo colors, can be displayed.

An image observed from the front side (relief structure-forming layer 10side) and an image observed from the back side (light scattering layer40 side) are displayed at completely the same position on the front andback. For example, when an analogous image is formed on one surface ofthe display 1 by means such as of a printing method, it is verydifficult to achieve complete coincidence in the positions of the imageson the front and back. On the other hand, the display 1 of the presentembodiment enables display with complete coincidence in the positions onthe front and back. The authenticity of the display 1 can also bedetermined by examining the offset in the positions of images on thefront and back.

The light reflection layer 30 that is at least partially formed inconformity with the shape of the concavo-convex structure of the reliefstructure-forming layer 10 contributes to more strongly reflecting theincident light. It is desirably so configured that, as shown in FIG. 15,the light reflection layer 30 is provided in conformity with the shapesof the plurality of convexities 20 formed on the reliefstructure-forming layer 10, with the smoothness of the first and secondsurfaces 21 and 22 being retained, and the surface of the lightreflection layer 30 on the first surface 21 is parallel to the surfaceof the light reflection layer 30 on the second surface 22.

FIG. 16 shows the case where the light reflection layer 30 has a roughsurface and the smoothness of the light reflection layer 30 on the firstand second surfaces 21 and 22 is not retained. FIG. 17 shows the casewhere the light reflection layer 30 is unevenly laminated on the firstand second surfaces 21 and 22. In the cases shown in these figures,interference is caused and enlarges a light wavelength range where thediffraction efficiency is lowered. As a result, the chroma of anobtained display color is lowered and thus the display color exhibits awhite color which is not substantially different from the wavelengthdistribution of the incident light.

Desirably, the light reflection layer 30 has a thickness of not lessthan 30 nm but not more than 70 nm, more preferably 50 nm. The lightreflection layer 30 can be formed into a thin shape by a vapor phasedeposition method. However, a thin film of metal, such as aluminum, goldor silver, will have a surface which tends to cause granular unevennesswith a particle size of about 1 μm. The granular unevenness is moreeasily enlarged as the formed layer has a larger thickness. On the otherhand, when a formed layer is excessively thin, sufficient lightreflection performance is no longer achieved. An ideal thickness of thelight reflection layer 30 obtained through experiments was not less than30 nm but not more than 150 nm. When the thickness of the lightreflection layer 30 is set so as to fall within this range, it ispossible to achieve both sufficient light reflection performance of thelight reflection layer 30 and a smoothness in the surface of the lightreflection layer 30 on the first and second surfaces 21 and 22.

The light scattering layer 40 contains, for example, a lighttransmissive synthetic resin and fine spherical microparticles havinglight scattering performance. The light scattering layer 40 that ispermitted to contain spherical microparticles can sufficiently scatterthe light of a specific wavelength and the specular reflection emittedfrom the relief structure-forming layer 10 to thereby obtain lightscattering performance sufficient for emitting white light. Bycontrolling the particle size and/or the quantity of the sphericalmicroparticles to be filled in, the light scattering performance can beadjusted as desired. In order to sufficiently scatter the incidentlight, the spherical microparticles may have a particle size that isapproximately the same as the incident wavelength. When the incidentlight is visible light having a wavelength of 460 to 640 nm, thespherical microparticles may have a size, for example, of about 500 nm.

At the same time with scattering incident light, the light scatteringlayer 40 has a function of transmitting the incident light therethrough.Therefore, the spherical microparticles may be scattered within thelayer with an interval of some extent therebetween. The filling densityof the spherical microparticles within the layer is typically 50%.

Besides the spherical microparticles, the light scattering layer 40 mayfurther contain microparticles in other shapes, such as needle shapes orelliptic shapes, or microparticles having surfaces each of which isprovided with fine projections or unevenness, or the like. Further, thelight scattering layer 40 may further contain a light transmissivematerial. The light transmissive materials that can be used include anink or a toner composed of a pigment or a dye, and a fibrous material,such as cellulose or starch.

In order to use the display 1 as a label, the light scattering layer 40may be an adhesive layer. When the light scattering layer 40 is formedas an adhesive layer, the display 1 can be stuck onto an informationdisplay medium or other articles by means of the light scattering layer40. When the display 1 is stuck onto a transparent printed object (e.g.,plastic card) or a transparent article having light transmissionperformance, the display 1 can be observed from the back side via thetransparent printed object and the article.

The light scattering layer 40 may have light scattering performancewhich is substantially uniform within a unit volume. When the lightscattering layer 40 has light scattering performance which issubstantially uniform within a unit volume, the light scatteringperformance of the light scattering layer 40 can be controlled byadjusting the thickness of the layer.

When the light scattering layer 40 is permitted to have light scatteringperformance which is substantially uniform within a unit volume, thelight scattering layer 40 may have a haze value of not less than 80%.The haze value refers to a value that indicates a turbidity (haziness)when light is transmitted through a layer, such as a film, and isdetermined by the surface roughness of the layer and/or the scatteringcomponents inside the layer. A method of measuring the haze value isshown in optical characteristics testing methods for plastic (JISK7136:2000). The haze value is calculated from a ratio of diffusedtransmitted light to total transmitted light, which is defined by thefollowing Formula (3).

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack & \; \\{{{Haze}\lbrack\%\rbrack} = {\frac{T_{d}}{T_{t}} \times 100}} & (3)\end{matrix}$

In the formula, Td represents a diffuse transmittance, and Tt representsa total light transmittance.

When the haze value of the light scattering layer 40 is permitted to benot less than 80%, the light of a specific wavelength and the specularreflection emitted from the relief structure-forming layer 10 can bewell scattered and the emission light can be turned to white scatteringlight.

The total light transmittance Tt of the light scattering layer 40 may benot less than 30%. The total light transmittance is a percentage of thequantity of light transmitted through the light scattering layer 40 tothe quantity of light emitted from the relief structure-forming layer10. When the total light transmittance Tt of the light scattering layer40 is permitted to be not less than 30%, a display color that isdifferent from the front side can be achieved without unnecessarilyblocking the light emitted from the relief structure-forming layer 10.It is better that the haze value and the total light transmittance Tt ofthe light scattering layer 40 are both high. A haze value and a totallight transmittance Tt both approximate to 100% can achieve a monochromedisplay closer to a white color.

When light scattering elements are distributed within the layer in anon-uniform manner and when the light scattering elements each have ashape and/or a size that are altered in the layer, the light scatteringperformance of the light scattering layer 40 is no longer uniform in aunit volume. When the light scattering performance of the lightscattering layer 40 is non-uniform in a unit volume, the density,distribution, shape and/or size of the light scattering elements may beadjusted to suppress the degree of scattering the light having anoptional hue, which is emitted from the relief structure-forming layer10. The light scattering performance of the light scattering layer 40may be controlled by a plurality of means to produce a more complicatedimage as observed from the back side of the display 1.

In this way, the display 1 having the relief structure-forming layer 10,the light reflection layer 30 and the light scattering layer 40according to the present embodiment is able to exert special visualeffects which the conventional art could not achieve. More specifically,the display 1 of the present embodiment enables color display ofmultiple colors as observed from the front side and enables chromatic toachromatic (monochromatic) gradation display in accord with thethickness of the light scattering layer 40 as observed from the backside. Thus, the display 1 of the present embodiment can achieve highanti-counterfeiting effects.

Second Representative Embodiment

The area-specific change in the light scattering performance of thelight scattering layer 40 also enables display of visually recognizableinformation, such as a design, letter, numeral, and symbol. FIGS. 18Aand 18B each show an example of a display 1 which displays informationthat is visually recognizable using differences in the light scatteringperformances of a light scattering layer 40.

FIG. 18A shows a pattern of relief structure-forming areas 211 to 215configuring the display 1. As shown in FIG. 18B, the reliefstructure-forming areas 211 to 251 have the same height inconcavo-convex structure, while having virtual planes 311 to 315 ofdifferent heights. A light scattering area 235 for displaying a letter“A” has the light scattering layer 40 of a large thickness, compared tolight scattering areas 231 to 234 which display a background portion.Accordingly, the light scattering area 235 has high light scatteringperformance and thus is able to well scatter the light emitted from therelief structure-forming layer 10.

The light scattering areas 231 to 234 have low scattering performance,compared to the light scattering area 235. Since the light scatteringperformance of the light scattering areas 231 to 234 is permitted tochange stepwise, the light scattering areas 231 to 234 correspond toscattering variable areas which are able to transmit the light emittedfrom the relief structure-forming layer 10 with any light quantity. Thethickness of the light scattering layer 40 sequentially increases fromthe light scattering area 231 to the light scattering area 234 tothereby increase the light scattering performance. In other words, theheights of the virtual planes 311 to 314 configured by the top surfaces(first surface) of the convexities, relative to a base surface 130 aresequentially decreased from the light scattering area 231 to the lightscattering area 234.

When the display 1 of the present embodiment is observed from the backside, a display as shown in FIG. 19 is observed. The letter “A” shown inFIG. 19 is an image in white color displayed by the light scatteringarea 235. The background portion of the letter “A” provides a chromaticcolor display created by the relief structure-forming areas 211 to 214that are laid under the light scattering layer 40 as viewed from theobserver. The light scattering performance in the background portionchanges stepwise, and thus the chromatic color display created by therelief structure-forming areas 211 to 214 is not sufficiently scatteredenough to provide a multistep hue in pastel. The light scattering area234 on the left of the display 1 exhibits high light scatteringperformance and thus no chromatic color display created by the reliefstructure-forming area 214 can be seen, but a display approximate towhite color can be observed. However, the light scattering performanceof the light scattering areas 233 to 231 lowers stepwise toward theright of the display 1, and thus the chromatic color display created bythe relief structure-forming areas 213 to 211 can be observed stepwise.In the example shown in FIGS. 18A, 18B and 19, the background portion isconfigured by four types of relief structure-forming areas and lightscattering areas. However, use of more number of types of reliefstructure-forming areas and light scattering areas can provide asmoother gradation display.

On the other hand, when the display 1 of the present embodiment isobserved from the relief structure-forming layer 10 side, the display 1provides only a display with a uniform chromatic color, as shown in FIG.18A, created by the relief structure-forming areas 211 to 215, andneither the letter “A” nor the gradation display around the letter canbe observed. This is because the concavo-convex structures of the reliefstructure-forming areas 211 to 215 have the same height.

In this way, the display 1 of the present embodiment can displaycompletely different images on the front and back, instead of the imagesof a mirror-image relationship with different display colors as obtainedin the first embodiment. This effect is ascribed to varying the lightscattering performance of the light scattering layer 40 in accord withthe thickness thereof, and forming visually recognizable information bythe variation of the thickness. Accordingly, the display 1 of thepresent embodiment can exert special visual effects and highanti-counterfeiting effects, which have not been achieved based on theconventional art.

Third Representative Embodiment

FIG. 20 is a cross-sectional view illustrating a configuration of adisplay 1 related to a third embodiment of the present invention.

The display 1 of the present embodiment is different from the display 1of the first embodiment in that a printed layer 50 and a surfaceprotective layer 51 are further provided. The printed layer 50 and thesurface protective layer 51, which realize other functions, can beappropriately added to any interface of the layers.

The printed layer 50 can be provided on a surface of the reliefstructure-forming layer 10 or the light scattering layer 40 of thedisplay 1. The aesthetic quality of the display 1 can be improved byproviding the printed layer 50. Also, information to be displayed on thedisplay 1 can be easily added by providing the printed layer 50. It ispreferable that the printed layer 50 is partially provided so as not toentirely cover the display on the display 1. The printed layer 50 may beformed using an invisible ink that allows concealed information to bereproduced by ultraviolet or infrared light emission, or a functionalink, such as a light absorbing ink. Alternatively, the printed layer 50may be provided on some other functional layer, such as the surfaceprotective layer 51 described below, or may be provided between therelief structure-forming layer 10 or the light scattering layer 40 andsome other functional layer.

The surface protective layer 51 may, for example, be a hard coat layerthat prevents breakage of the relief structure-forming layer 10, or anantifouling layer that prevents attachment of dirt or fingerprints.Provision of such a layer can prevent the surface of the display 1 frombeing broken or becoming dirty and thus can prevent damage to the imageand information displayed by the display. For example, the surfaceprotective layer 51 is provided to an outermost surface of a laminatedstructure of the display 1. The surface protective layer 51 maypreferably be formed of a transparent or semi-transparent, desirably,colorless and transparent material so as not to impair visibility of thedisplay 1.

Referring to FIGS. 21 and 22, differences in display pattern arediscussed below to thereby discuss the effects of the presentembodiment.

FIG. 21 is a plan view illustrating the front side of the display 1. Onthe left of the display 1, a pattern is formed by the reliefstructure-forming layer 10 (relief structure-forming areas 11 and 12),while on the right of the display 1, a pattern is formed by the printedlayer 50 in color. When the display 1 is observed from the front side(the relief structure-forming layer 10 and the printed layer 50 side), apattern of “TP” in color display can be observed on both of the left andright sides of the display 1.

On the other hand, the light from the relief structure-forming layer 10passes through the light scattering layer 40 and thus when observed fromthe back side, a hue which is different, as shown in FIG. 22, from theone observed from the front side, specifically, an achromatic colordisplay of lower chroma is obtained. On the other hand, the light fromthe printed layer 50 is attenuated to some degree in chroma when passingthrough the light scattering layer 40, but the color display isretained. Accordingly, when observed from the front side, the “TP”pattern in color is obtained on both of the relief structure-forminglayer 10 and the printed layer 50. From the back side, a monochromedisplay of the “TP” pattern created by the relief structure-forminglayer 10 and the “TP” pattern in color display created by the printedlayer 50 are obtained. It should be noted that the surface protectivelayer 51 is colorless and transparent and thus does not influence thevisual effects of the display 1.

When the configuration shown in FIG. 20 is used, it is desirable thatthe light reflection layer 30 be “semi-transmissive” in order to enableobservation of the printed layer 50 through the light reflection layer30. The “semi-transmissive” light reflection layer 30 of the presentinvention has a visible light transmittance of not less than 25%,preferably 50% to 75%. To make the light reflection layer 30“semi-transmissive”, the light reflection layer 30 may desirably satisfya condition, for example, of having a thickness of not more than 30 μm.Alternatively, the light reflection layer 30 does not have to benecessarily formed in the area where the printed layer 50 is formed.

According to the present embodiment, the pattern displayed by the reliefstructure-forming layer 10 is monochromatically displayed by beingpassed through the light scattering layer 40. On the other hand, thepattern displayed by the printed layer 50 is displayed with the samecolor in spite of its being passed through the light scattering layer40. Accordingly, when observed from the back side, in a part of theobservation, display (color display) that is the same as the oneobserved from the front side is obtained, and in a part of theobservation, display (color display and monochromatic display) that isdifferent from the one observed from the front side is obtained. Thus,the display 1 of the present embodiment is able to achieve specialvisual effects and high anti-counterfeiting effects which cannot beachieved by the conventional art.

In the event that a counterfeit product of the present display of atwo-layer configuration including the printed layer 50 and the lightscattering layer 40 goes in circulation, the difference between agenuine product and the counterfeit product is quite obvious when thedisplay is observed from the back side (light scattering layer 40 side).

Fourth Representative Embodiment

(How to Use the Display)

The display can be provided to a base, such as a paper sheet and aplastic film, or some other article, for observation from both of thefront and back surfaces. In such a case, it may desirably so configuredthat the base or some other article is provided with an opening orprovided with a window which enables visual contact from the front andthe back, so that the display can be observed.

The display 1 described above may be used as a anti-counterfeiting labelby permitting the light scattering layer 40 to serve as an adhesivelayer. Alternatively, the display 1 may be stuck onto a printed objector some other article by means of a separately provided fixing means.The display 1 can display a unique color by strictly controlling thesmoothness of the first and second surfaces of convexities orconcavities configuring the fine concavo-convex structure, and thedifferences in height between the surfaces. Further, when the display 1is observed from the back side via a light transmissive base or someother article, display with a different hue can be confirmed. Since itis difficult to highly accurately reproduce these visual effects, it isvery difficult to counterfeit the display 1. When this label is carriedby an article, the article with the label, i.e. a genuine product, it isalso difficult to counterfeit or imitate it.

FIG. 23 is a plan view schematically illustrating an example of anarticle with a label in which the display 1 is carried by the article.FIG. 24 is a cross-sectional view taken along a line XXIV-XXIV of thearticle with a label illustrated in FIG. 23.

FIGS. 23 and 24 show an IC (integrated circuit) card 70 as an example ofthe article with a label. The IC card 70 includes a light transmissivebase 71. The base 71 is made, for example, of plastic. The base 71 hasone base surface 74 which is provided with a recess into which an ICchip 72 is fitted. The IC chip 72 has a surface which is provided withelectrodes. Information can be written into the IC and information canbe read from the IC via these electrodes. A printed layer 73 is formedon the base 71. The display 1 of any of the first to third embodimentsis stuck onto the surface of the base 71, on which the printed layer 73is formed. The display 1 may be in the form of a label in which, forexample, the light scattering layer 40 is an adhesive layer. In thiscase, the light scattering layer 40 can be stuck onto the printed layer73 to fix the display 1 to the base 71. Alternatively, the display 1 maybe used as a transfer foil and stuck onto the printed layer 73 by meansof a separately provided adhering means, thereby fixing the display 1 tothe base 71.

The IC card 70 includes the display 1. Therefore, it is difficult tocounterfeit or imitate the IC card 70. Further, in addition to theanti-counterfeiting effects of the display 1, the IC card 70 can adoptan anti-counterfeiting measure making use of the IC chip 72 and theprinted layer 73. Thus, according to the present embodiment, attachmentof the display 1 described in any of the first to third embodiments tothe IC card 70 can achieve anti-counterfeiting effects in a manner ofelectronic data, as well as anti-counterfeiting effects in a visualmanner.

Although FIGS. 23 and 24 show an example of an IC card as a printedobject including the display 1, a printed object including the displayis not limited to this. For example, a printed object including thedisplay may be: other cards, such as a wireless card and an ID(identification) card; valuable stock certificates, such as papercurrency and gift tickets; a tag which is attached to an article thatshould be confirmed as being a genuine product; or a package or a partthereof which accommodates an article that should be confirmed as beinga genuine product.

Further, an article with a label does not necessarily have to be aprinted object. In other words, the display may be carried by an articlethat does not include the printed layer 73. For example, the display 1may be carried by luxury articles, such as works of art. The display 1may be used for purposes other than anti-counterfeiting. For example,the display 1 may be used as a toy, learning material or an ornament.

Modifications

It should be noted that the present invention should not be construed asbeing limited to the embodiments described above.

The number of the relief structure-forming areas provided to the reliefstructure-forming layer 10 is not limited to the number described in theabove embodiments, but more number of types may be provided to thelayer.

In the above embodiments, the relief structure-forming layer 10 isformed by processing an upper surface of a light transmissive base. Asanother method, the relief structure-forming layer 10 may be provided ona light transmissive base which is different from the reliefstructure-forming layer 10. Also, the material and the thickness of thelight scattering layer 40 may be appropriately determined according to aneeded transmission quantity and scattering quantity. Further, thematerials of the spherical microparticles, the adhesive layer and thebase can be appropriately changed according to specifications.

Various modifications of the present invention may be implemented withina scope not departing from the spirit of the present invention.

INDUSTRIAL APPLICABILITY

The present invention can be used as a display that exhibitsanti-counterfeiting effects.

REFERENCE SIGNS LIST

-   1 Display-   10 Relief structure-forming layer-   11-14, 211-215 Relief structure-forming areas-   15-18, 231-235 Light scattering areas-   20 Convexity-   21 First surface-   22 Second surface-   30 Light reflection layer-   40 Light scattering layer-   50 Printed layer-   51 Surface protective layer-   60 Light source-   61 White illumination-   62 Light of a specific wavelength-   63 Specular reflection-   64 Scattering light-   65 Observer-   70 IC card-   71 Base-   72 IC chip-   73 Printed layer-   74 Base surface-   110 Base surface-   111-114, 311-315 Virtual planes-   d Pitch of a diffraction grating-   DL Diffracted light-   DL_r Diffracted light (red)-   DL_g Diffracted light (green)-   DL b Diffracted light (blue)-   GR Diffraction grating-   IL Illumination-   LS Light source-   NL Normal line-   RL 0-order diffracted light (specular reflection)-   α Incident angle-   β₁₃r Incident angle of diffracted light with wavelength component R-   β_g Incident angle of diffracted light with wavelength component G-   β_b Incident angle of diffracted light with wavelength component B

What is claimed is:
 1. A display comprising: a relief structure-forminglayer having a plurality of relief structure-forming areas that areprovided on one principal surface side of a light transmissive base; alight reflection layer covering at least a part of the reliefstructure-forming layer; and a light scattering layer provided by a sideof the light reflection layer of the relief structure-forming layer,being imparted with light transmission performance, while being impartedwith light scattering performance in at least a part thereof, wherein:the plurality of relief structure-forming areas have a plurality ofconvexities or a plurality of concavities having a first surfacesubstantially parallel to the principal surface and a second surfacesubstantially parallel to the first surface; the light reflection layeris formed in conformity with a shape of the plurality of convexities orconcavities; in each of the plurality of relief structure-forming areas,a difference in height between the first surface and the second surfaceis substantially constant; in each of the plurality of reliefstructure-forming areas, at least one of a distance between the firstsurface and the second surface or a distance between the lighttransmissive base and a virtual plane extending along the first surfaceis different from a distance between a top surface and a bottom surfaceof other relief structure-forming areas or a distance between the lighttransmissive base and a virtual plane of the other reliefstructure-forming areas; the plurality of relief structure-forming areasare arranged in accordance with a color image to be displayed; and areasof the relief-structure forming layer that are not covered with thelight reflection layer are covered by the light scattering layer.
 2. Thedisplay according to claim 1, wherein each of the plurality of reliefstructure-forming areas, a distance between the light transmissive baseand a virtual plane configured by the first surface is different from aheight of the virtual plane in other relief structure-forming areas. 3.The display according to claim 2, wherein the light scattering layerincludes a plurality of light scattering areas having differentthicknesses and corresponding to the relief structure-forming areas. 4.The display according to claim 1, wherein the display comprises aprinted layer in color.
 5. The display according to claim 1, wherein thelight scattering layer contains spherical micro-particles having lightscattering performance.
 6. The display according to claim 1, wherein thelight scattering layer is an adhesive layer.
 7. The display according toclaim 1, wherein the light scattering layer has light scatteringperformance which is substantially uniform in a unit volume.
 8. Thedisplay according to claim 1, wherein the light scattering layer has ahaze value of not less than 80% and a total light transmittance of notless than 30%.
 9. An article comprising a label thereon, wherein thelabel comprises a display according to claim
 1. 10. The displayaccording to claim 1, wherein the plurality of convexities orconcavities are arranged with regular intervals therebetween such that awidth of an interval between adjacent convexities or concavities is 5-10μm.
 11. The display according to claim 10, wherein the plurality ofconvexities or concavities are arranged at equal distances from eachother, such that each one of the convexities or concavities is spaced atan even interval from another one of the convexities or concavities, forall of the plurality of convexities or concavities, and the plurality ofconvexities each have an upper surface having a circular perimeter and acylindrical side surface projecting above a base of the reliefstructure-forming layer.
 12. The display according to claim 1, whereinthe light scattering layer has light scattering performance which issubstantially non-uniform in a unit volume.
 13. The display according toclaim 12, wherein the light scattering performance is obtained by lightscattering elements of the light scattering layer and not therelief-structure forming layer.
 14. The display according to claim 1,wherein the relief structure-forming layer is configured to emit lightof a chromatic color according to a specific wavelength which isdetermined by the difference in distance between the top and bottomsurfaces.
 15. The display according to claim 1, wherein, when thedisplay is viewed from a side not provided with the light scatteringlayer, a chromatic display is visible.
 16. The display according toclaim 15, wherein, when the display is observed from the side providedwith the light scattering layer, a monochromatic display is visible. 17.The display according to claim 15, wherein the plurality of convexitiesor the plurality of concavities are structured so as to have a pluralityof grating constants.
 18. The display according to claim 17, wherein theplurality of convexities or the plurality of concavities are structuredsuch that light beams of differing wavelengths are emitted at varyingangles so as to be superimposed with each other.